Effect of aspect ratio on mechanical anisotropy of lattice structures

Abstract

Triply periodic minimal surface (TPMS) lattice structures with controllable mechanical properties and porous architecture are promising candidates for lightweight and energy-absorbing applications. In parametric structural design, the research on structural geometric characteristics, such as aspect ratio (R) and surface curvature, has mainly focused on fluid and heat transfer considerations. However, their impact on multi-directional mechanical properties has yet to be thoroughly investigated. This study, combining representative volume elements (RVE) based on periodic boundary conditions and theoretical surface morphological characteristics, investigates the mechanical properties and deformation behavior of lattice structures with different aspect ratios in multiple directions. The results indicate that the aspect ratio highly influences the deformation behavior of the lattice structure in different directions. The local curvature and force state of the lattice structure can be adjusted by aspect ratio to reduce local stresses and deformations in different loading directions. Compared with the simulation results of representative volume elements, the structural stress concentration and failure position can be predicted by the Gaussian curvature distribution. In addition, the elastic modulus of the structures in the [100] and [001] directions can also be adjusted by aspect ratio. Through experimental verification in the [001] direction, the structure with an aspect ratio of 2 can greatly enhance the elastic modulus (121%∼440%), maximum stress (10%∼183%), and energy absorption (33%∼85%). The significance of this work is to improve the understanding of the influence of geometric features on the mechanical properties and deformation behavior of lattice structures, which provides a new design approach for triply periodic minimal surface lattice structures in applications of impact protection and bone scaffold.